EMISSION AND BURIAL POTENTIAL OF BLUE CARBON HABITATS IN FINNISH LAKES

Boreal lakes represent an important long-term carbon sink and pose as major candidates for nature-based solutions to mitigate climate change through carbon sequestration. At the same time lakes are recognized as large sources of atmospheric carbon and previous studies have shown a weak linear relationship between lake sediment carbon emission and burial rate. In coastal marine environments shallow water vegetated areas, or so called “blue carbon” habitats, may sequester as much as 50% of the total global marine carbon, but have also been shown to act as sources for greenhouse gases such as methane. The carbon fluxes of equivalent blue carbon habitats in lacustrine environments remains largely unexplored. In this study we aim to quantify sediment carbon burial and remineralization rates in Finnish lakes, both in blue carbon habitats dominated by the macrophyte Phragmites australis, and deeper open water areas. Initial results suggest that shallow water vegetated areas host considerable sediment carbon stocks, although the deposits are thinner in vertical extent and of overall smaller magnitude than stocks in deep open water areas. Porewater analysis shows that upwards diffusive fluxes of TCO₂, DOC and CH₄ occur in both shallow and deep-water areas. Relative rates of release of these three fractions are controlled by redox conditions. Due to the short water column, blue carbon habitats emit more dissolved carbon directly into the surface water than do the sediments of deeper open water areas.

Presentation Preference: Poster

Primary Presenter: Max Kankainen, University of Helsinki (max.kankainen@hotmail.com)

Authors:

Max Kankainen, Department of Geosciences and Geography, Faculty of Science, University of Helsinki, Helsinki, Finland  (max.kankainen@helsinki.fi)

Ana Lúcia Dauner, Department of Geosciences and Geography, Faculty of Science, University of Helsinki, Helsinki, Finland  (ana.lindrothdauner@helsinki.fi)

Tuomas Junna, Geological Survey of Finland, Espoo, Finland  (tuomas.junna@gtk.fi)

Marie Korppoo, Finnish Environment Institute, Helsinki, Finland  (marie.korppoo@syke.fi)

Asko Simojoki, Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland  (asko.simojoki@helsinki.fi)

Karoliina Koho, Geological Survey of Finland, Espoo, Finland  (karoliina.koho@gtk.fi)

Tom Jilbert, Department of Geosciences and Geography, Faculty of Science, University of Helsinki, Helsinki, Finland  (tom.jilbert@helsinki.fi)